1. Field of the Invention
The present invention relates to radiation beam therapy systems, and more particularly to a radiation treatment system with a patient positioner. The present invention relates to radiation beam therapy systems, and more particularly to a modular patient support system. The present invention relates to radiation beam therapy systems, and more particularly to a patient pod with tapered edge configurations that reduce edge effects associated with abrupt changes in the water equivalency in the radiation beam path.
2. Description of the Related Art
Radiation therapy systems are known and used to provide treatment to patients suffering a wide variety of conditions. Radiation therapy is typically used to kill or inhibit the growth of undesired tissue, such as cancerous tissue. A determined quantity of high-energy electromagnetic radiation and/or high-energy particles are directed into the undesired tissue with the goal of damaging the undesired tissue while reducing unintentional damage to desired or healthy tissue through which the radiation passes on its path to the undesired tissue.
Proton therapy has emerged as a particularly efficacious treatment for a variety of conditions. In proton therapy, positively charged proton subatomic particles are accelerated, collimated into a tightly focused beam, and directed towards a designated target region within the patient. Protons exhibit less lateral dispersion upon impact with patient tissue than electromagnetic radiation or low mass electron charged particles and can thus be more precisely aimed and delivered along a beam axis. Also, upon impact with patient tissue, protons exhibit a characteristic Bragg peak wherein a significant portion of the kinetic energy of the accelerated mass is deposited within a relatively narrow penetration depth within the patient. This offers the significant advantage of reducing delivery of energy from the accelerated proton particles to healthy tissue interposed between the target region and the delivery nozzle of a proton therapy machine as well as to “downrange” tissue lying beyond the designated target region. Depending on the indications for a particular patient and their condition, delivery of the therapeutic proton beam may preferably take place from a plurality of directions in multiple treatment fractions to maintain a total dose delivered to the target region while reducing collateral exposure of interposed desired/healthy tissue.
U.S. Pat. No. 4,870,287, issued Sep. 26, 1989, assigned to the Loma Linda University Medical Center, titled MULTI-STATION PROTON BEAM THERAPY SYSTEM, describes and illustrates a radiation beam therapy system. The system described therein includes several different treatment stations, each including a gantry for supporting and rotating a radiation beam transport and delivery system on an axis of rotation around a stationary patient to deliver a treatment beam to a predetermined target isocenter within the patient from several different angles.
With many radiation treatment systems and protocols, a unique treatment plan is first developed for each cancer patient. For example, in the development of a treatment plan, such as, for example, proton radiation treatment, the patient is generally positioned on a support table or support structure and the internal anatomy of the patient's body scanned with an imaging technique, such as, for example, computed tomography (CT Scan). Images produced by the imaging device are analyzed to precisely locate the cancer sites defining the targets for the radiation beams. In many cases, physicians develop a radiation treatment plan calling for a number of different patient treatment sessions with radiation beams of different magnitudes, durations and angles of direction.
Given the high number of cancer patients who could benefit from radiation treatment and the relatively few number of sophisticated radiation (e.g., proton) treatment facilities and systems available in the world, there is a need for radiation treatment providers to achieve greater patient throughput at their existing facilities. As such, there is a need for patient support and positioning systems that utilize automated or robotic patient positioning devices, and thereby provide radiation treatment providers with the ability to achieve increased patient throughput.
For each treatment session, it is important that the patient be supported in the exact same position as during the preliminary imaging or scanning session utilized in the development of the treatment plan (i.e., the original position). Accordingly, there is a need for a patient positioning and repositioning support system for fixedly securing a patient in an original position during radiation treatment and for repositioning the patient in the same original position during any subsequent radiation treatment sessions. For certain applications that involve irradiating different portions of a patient's anatomy from several different angles, it is desirable for the patient positioning and repositioning support to fixedly secure the patient.
The radiation treatment protocol for any given patient can depend on a number of factors, including, for example: the size and physical characteristics of the patient; the type, size, and location of the tumor(s) being irradiated; and the aggressiveness of the treatment protocol. As such, there is a need for a modular patient support system that can be easily adjusted to accommodate a large number of treatment protocols.
For certain treatment protocols it is necessary to direct the radiation beam at angles that traverse at least one lateral edge of the patient pod. Accordingly, there is a need for pod edge configuration that reduces discontinuities in the strength or intensity of radiation beams that pass through or near a pod lateral edge.